Why the fascination with the ‘datumses’? Does it seem crazy? Suppose:
an hour and a half after first light, you spot three birds crossing the track between my front fence and the highway. Heading east.
Hmmm . . . well, they are between A and Z. ‘A’ was probably their roost; but that roost would have been near the last pasture they grazed on yesterday afternoon. The 500? Oudman’s? (This is the point, guys – those are the only two pastures in the vicinity.)
Both seem unlikely because there are fences and roads to cross. Where then?
Where is ‘Z’? The one thing we can be sure enough of is that they are ‘transiting’ through the strip of bush between my front fence and the highway. It isn’t their goal – it’s starvation scrub.
They aren’t going to cross the highway to get into the National Park – why would you expend so much energy to gain so little food?
Well, they may be going down to the swamp paddock or the corridor – but again, it’s a long way to run the chance of getting flogged by the locals (unless these travelling birds have a big territory, and are the corridor birds!!).
Well, guys . . . I don’t know – but I have been thinking about it all day.
Here’s a simpler one: Speckles and Sarah snuck into the house-clearing.
[And I got my first really good look at Speckles, by the way. He’s a big bird – very ‘beamy.’ Some birds are remarkably tall and skinny. Some are much broader in the body. Sarah’s neck markings are most unusual. The sheen on the patch at the top of her neck is a wet-fish-silver colour.]
And why do they vocalise? Why don’t they just gobble and shut up? Eric Plus shunted them off. I then headed off with the Old Man Barrow (patent pending) to get some garden sand down near Meadow Two. Saw S. and S. ‘curving’ through the gums. Put the barrow down, and waited ten minutes. Snuck down to Meadow Two. Bingo, they were grazing there!
So, they leave the house-clearing heading south, travelling at walking-speed. We see them at another point. The best guess is that they are ‘arcing’ down to the next pasture.
Thinking about stuff like this helps figure out when and why birds cross fences; what the population density is; how far they travel in a day, at what speed, to how many pastures.
All questions are ultimately entwined: suppose a non-alpha bird hears birds close by at dawn. Can that first bird identify the other birds? and know their status? Would that mean that the first bird would head off to a pasture where he won’t encounter an alpha bird? Perhaps this goes on during the day? Perhaps birds are taking cues, about where they will try to graze, from the vocalisations of (known and unknown) birds around them. (Wow! Can you vocalise ‘alpha-ness’??)
Supreme Emu
